Case Study of Phrenic Nerve Paralysis: “I Can't Breathe!”

BackgroundThe anatomic course of the phrenic nerve runs in the fascia covering the anterior scalene muscle. Interscalene blocks are commonly performed by an anesthesiologist for shoulder surgery, such as a rotator cuff repair, total shoulder replacement, humeral fracture, or other arm surgery. Phrenic nerve palsy or paralysis is a known complication from interscalene block and is covered in multiple case reports and series in both Anesthesia and Neurosurgical literature, but only one case report in the Emergency Medicine literature.Case ReportThis case involves a 57-year-old man who had an uncomplicated arthroscopic rotator cuff repair with placement of interscalene block under care of anesthesia. He was discharged with a pain pump in place and then subsequently presented to the Emergency Department (ED) later that same day for evaluation of dyspnea. Using point-of-care ultrasound, his right diaphragm did not appear to be moving. Chest x-ray study revealed an elevated right hemidiaphragm. He was diagnosed with iatrogenic right phrenic nerve paralysis from interscalene block.Why Should an Emergency Physician Be Aware of This?Emergent diagnosis of phrenic nerve paralysis in the ED is complicated by a distressed patient and need for quick intervention. Most formal tests for this diagnosis are not immediately available to emergency physicians. Ultrasound is a rapid and reproducible, noninvasive resource with high sensitivity and specificity, making it an ideal imaging modality for the emergent evaluation of possible phrenic nerve palsy or paralysis.     

Calcium release near l-type calcium channels promotes beat-to-beat variability in ventricular myocytes from the chronic AV block dog

Beat-to-beat variability of ventricular repolarization (BVR) has been proposed as a strong predictor of Torsades de Pointes (TdP). BVR is also observed at the myocyte level, and a number of studies have shown the importance of calcium handling in influencing this parameter. The chronic AV block (CAVB) dog is a model of TdP arrhythmia in cardiac hypertrophy, and myocytes from these animals show extensive remodeling, including of Ca^2 + handling. This remodeling process also leads to increased BVR. We aimed to determine the role that (local) Ca^2 + handling plays in BVR.In isolated LV myocytes an exponential relationship was observed between BVR magnitude and action potential duration (APD) at baseline. Inhibition of Ca^2 + release from sarcoplasmic reticulum (SR) with thapsigargin resulted in a reduction of [Ca^2 +]_i, and of both BVR and APD. Increasing I_CaL in the presence of thapsigargin restored APD but BVR remained low. In contrast, increasing I_CaL with preserved Ca^2 + release increased both APD and BVR. Inhibition of Ca^2 + release with caffeine, as with thapsigargin, reduced BVR despite maintained APD. Simultaneous inhibition of Na⁺/Ca^2 + exchange and I_CaL decreased APD and BVR to similar degrees, whilst increasing diastolic Ca^2 +. Buffering of Ca^2 + transients with BAPTA reduced BVR for a given APD to a greater extent than buffering with EGTA, suggesting subsarcolemmal Ca^2 + transients modulated BVR to a larger extent than the cytosolic Ca^2 + transient.In conclusion, BVR in hypertrophied dog myocytes, at any APD, is strongly dependent on SR Ca^2 + release, which may act through modulation of the l-type Ca^2 + current in a subsarcolemmal microdomain.     

Liver Transplantation After Hematopoietic Stem Cell Transplant for the Treatment of Sickle Cell Disease: A Case Report

Sickle cell anemia is the most common of the hemoglobinopathies, in which the abnormal hemoglobin formed in deoxygenation states undergoes a polymerization process with consequent erythrocyte deformation and vaso-occlusive events. The need for multiple blood transfusions, prolonged ineffective erythropoiesis, hemolysis, and increased iron absorption can cause iron overload in the liver, leading to liver fibrosis. Hematopoietic stem cell transplantation (HSCT) is currently the only treatment with a curative potential for this disease and can establish normal complete or partial donor-derived erythropoiesis and stabilize or restore function in affected organs, preventing further deterioration of function. However, it does not reverse preexisting liver fibrosis and siderosis. One of the possible complications of patients who undergo HSCT is chronic liver disease, which has a multifactorial cause, with iron overload being an important factor. In the long term, the prevalence of chronic liver disease in HSCT patients, including cirrhosis and its complications, can be significant. Solid organ transplantation after allogeneic hematopoietic cell transplantation for end-organ failure remains a very rare event. It may offer a valuable treatment strategy in selected recipients, although it is associated with significant morbidity and mortality. We report the case of a patient with sickle cell anemia who underwent HSCT and developed severe liver dysfunction requiring liver transplantation 13 years after the procedure. We found no previous report in the literature of orthotopic liver transplant after HCT for the treatment of sickle cell disease.     

Resveratrol attenuates high-fat diet-induced non-alcoholic steatohepatitis by maintaining gut barrier integrity and inhibiting gut inflammation through regulation of the endocannabinoid system

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